词性剖析

Humans are often thought to be insensitive smellier compared with animals, but this is largely because, unlike animals, we stand upright.

为何but和because能同时用呢？对于but和because不可以连用是当它们都充当并列连词的时候吗？若是的话这里because就是充当表从的引导词（即从属连词），对吗？

but的用法和because无关！！！

but表示后面的分句和前面的分句是并列句。but后的分句为主系表结构，because从句是后一分句中的表语。